How a Tick Bite Can Give You a Red Meat Allergy
Scientists have found that lone star ticks can induce the allergy. Here's how to protect yourself.
Anywhere from 96,000 to as many as 450,000 people in the U.S. may have developed an allergy to red meat following the bite of a tick, according to 2023 data published by the Centers for Disease Control and Prevention.
The new research adds to the growing body of evidence showing that the lone star tick—which for years has been most prevalent in the southeastern U.S.—could be the cause of an allergy to a carbohydrate known as alpha-gal, which is found in red meat.
There’s no national system for keeping track of cases of this dangerous allergy, so the authors of the 2023 report stress that we don’t really know how common it is. But we do know that lone star ticks are spreading—they can now be found as far north as Canada—and are becoming numerous in areas such as New York and New Jersey where, decades ago, they used to be scarce. That means more people may encounter them.
Here’s what you need to know about this allergy, which is sometimes called alpha-gal syndrome.
What Research Reveals
In the 2023 CDC study, researchers analyzed alpha-gal allergy test results for nearly 300,000 people tested between 2017 and 2022. They found that each year, an average of about 15,000 people in the U.S. were diagnosed with the red meat allergy.
Understanding Meat Allergies
It’s still not clear to scientists why a bite from a tick could cause a person to develop an allergy to red meat, or why some people who are bitten develop the allergy and others don’t.
There’s also an intriguing difference between the alpha-gal red meat allergy and every other type of food allergy. Typically, allergic reactions to food occur immediately after exposure, within a few minutes. With an alpha-gal allergy, however, a reaction typically doesn’t start until several hours after eating red meat—which can make it challenging to pinpoint the culprit.
And different people who do develop the allergy can have widely varying levels of sensitivity. Some may react only to mammalian meat (such as pork, beef, rabbit, lamb, venison, and more), while others may have reactions to cow’s milk (in which the alpha-gal molecule is also present), products made with milk, gelatin, or certain medications or vaccines made with gelatin or other animal ingredients.
What to Watch For
Recent research has found that people experiencing an allergic reaction to alpha gal often experience gastrointestinal (GI) symptoms, such as abdominal pain, diarrhea, and vomiting. In some cases, these may be the only symptoms, and a recent communication from the American Gastroenterological Association cautions that some people with an alpha-gal allergy may initially be misdiagnosed with irritable bowel syndrome or another GI illness.
Hives and itching also appear to be a common symptom of this allergy.
In some people, alpha-gal allergy—like many other allergies—can cause anaphylaxis, a serious and potentially deadly allergic reaction. Early signs of anaphylaxis may include a metallic taste, burning, tingling, or itching of the tongue or mouth, headache, and feelings of fear or confusion. A reaction can progress quickly, and severe symptoms include throat swelling, difficulty breathing, vomiting, diarrhea, and more.
If you think you may be experiencing anaphylaxis, even if you’ve never had an allergic reaction before, you should call 911. (If you know you have an allergy to food, and you experience symptoms of anaphylaxis, especially trouble breathing, wheezing, or throat swelling, you should use an epinephrine auto-injector if you have one.)
When the reaction is under control, talk to your doctor about whether red meat could have been the cause of your symptoms, since some doctors may not be aware of the alpha-gal allergy, suggests Princess Ogbogu, MD, director of the division of pediatric allergy, immunology, and rheumatology at University Hospitals Rainbow Babies & Children’s in Ohio.
There’s no cure for red meat allergy, so if you’re diagnosed, you’ll need to avoid the foods or medications, if applicable, that trigger a reaction.
In some cases, Lieberman says, if people who’ve developed alpha-gal allergies avoid all future tick bites from lone star ticks (as well as the ticks that cause the allergy in other countries), their levels of the antibodies to alpha-gal may diminish, and the allergy could subside. It’s unknown how common this is, however.
About the Lone Star Tick
Lone star ticks, so named for the white splotch on the backs of adult females, are most common in southern and eastern states. As with other ticks, however, their geographic distribution is expanding, according to Ellen Stromdahl, a retired entomologist from the tickborne disease laboratory of the U.S. Army’s Defense Center for Public Health-Aberdeen in Maryland.
Lone star ticks don’t cause Lyme disease. But along with spreading the alpha-gal allergy, they can also transmit a variety of other diseases, including the bacterial diseases ehrlichiosis and tularemia, which can both be fatal.
Tularemia and ehrlichiosis are both much rarer than, for example, Lyme disease (transmitted by the bite of a different tick species, the blacklegged tick). But lone star ticks are much more aggressive than other common types of ticks in the U.S. "You’re more likely to be mobbed by lone star ticks," Stromdahl says, and finding multiple bites is common if you’ve been in their habitat. (Read more about lone star ticks.)
Protect Yourself From Ticks
It’s important not to panic if you discover a tick bite, Lieberman says. "The vast majority in this country and elsewhere who get bitten by ticks don’t develop alpha-gal allergy," he says.
Still, you can take reasonable precautions to protect yourself from ticks and the diseases—or allergies—they can cause. Here’s what to do:
Wear an effective bug spray if you’re going to be in an area where ticks are common. Lone star and other types of ticks prefer wooded areas, brush, and long grass. Opt for EPA-registered repellents, which must demonstrate efficacy, rather than those made with only essential oils. Consumer Reports’ insect repellent testing has found that products containing 25 to 30 percent deet provide the longest-lasting protection. (Check our top-rated insect repellents.)
Try permethrin-treated clothing. You can buy clothes treated with the pesticide permethrin, have your own clothes professionally treated, or treat them yourself with permethrin spray. Studies show this can be a highly effective method of preventing tick bites. Just remember that permethrin mustn’t be used directly on your skin, so you’ll still want to use repellent on any exposed skin.
Dress carefully. Wear closed-toe shoes, wear long pants and long sleeves, and tuck your pants into your socks and your shirt into your pants. This can help prevent ticks from gaining access to your skin.
Check yourself for ticks at the end of every day you’ve been out in their territory. Taking a shower soon after you come in is a good opportunity to wash away any ticks that may be crawling on your skin without having yet bitten you, and to carefully look for any that have attached. If you find them on you, remove them properly.
Be careful with the clothes you wore when in a tick habitat. Stromdahl recommends you run them through a cycle in a hot dryer to kill any ticks that may be clinging on, and leave your shoes outside in the sun.
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